Field of the Invention
The present invention relates to a video signal transmission system, or more specifically, to a video signal transmission system for distributing video signals through a plurality of transmission paths.
Description of the Related Art
Video signals are transmitted by means of multicast in various cases where a video image shot with a camera installed in a stadium is transmitted to a broadcast station, and where a video image is transmitted from a broadcast station. When such a video signal is transmitted, the video signal is converted into IP packets, which are then transmitted through an IP network. Conventional IP transmission of the video signal has been based on the premise that a plurality of video streams are transmitted by using one network interface. For example, up to six HD (high definition) uncompressed transmission streams can be transmitted through the Ethernet (registered trademark) with a transmission rate of 10 Gbps.
Nonetheless, higher-definition and higher-volume video standards such as 4K and 8K are being put into practice in these years, and bit rates of these video signals are about to exceed bit rates in the conventional network infrastructure. For instance, 4K corresponds to a bit rate of 12 Gbps and cannot be transmitted through the 10-Gbps Ethernet. Further, 8K corresponds to a bit rate greater than 140 Gbps and cannot be transmitted even through the 100-Gbps Ethernet.
To deal with this problem, there is a technique called “link aggregation” to improve a communication speed and fault tolerance by regarding a plurality of transmission paths (Ethernet paths) virtually as one transmission path. Since the plurality of transmission paths are regarded as one transmission path, using the link aggregation can improve a bit rate by transmitting packets in parallel. For example, even when each Ethernet path has a transmission rate of 100 Gbps, it is possible to achieve a bit rate of 300 Gbps by aggregating three Ethernet paths of this type together (see KDDI R&D Laboratories, Inc., “Link Aggregation Radio Technology”, Technological Crossover, (August 2012), [online], KDDI R&D Laboratories Inc. Website, [Searched on Jul. 22, 2015], Internet (URL: http://www.kddilabs.jp/assets/files/technology/72.pdf), now available at http://www.juniper.net/techpubs/en_US/junose15.1/topics/concept/802.3ad-link-aggregation-understanding.html).